JP2017098301A - Optical module and method for manufacturing optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: an optical module which enables the increase in productivity while suppressing the worsening of reliability, and which enables the reduction in manufacturing cost; and a method for manufacturing the optical module.SOLUTION: An optical module 1 according to an embodiment comprises: a plurality of laser diodes (LDs) 21 to 23; a multiplexing optical system 30 for multiplexing a plurality of kinds of laser light from the plurality of LDs; and a package 10 housing the plurality of LDs and the multiplexing optical system. The package has: a support body on which the plurality of LDs and the multiplexing optical system are mounted; and a cap having a transmission window for passing multiplexed light therethrough. At least one LD has an oscillation wavelength of 550 nm or less. The moisture density in the package is 3000 ppm or less. The multiplexing optical system is fixed to the support body by a curable resin adhesive.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an optical module and a method for manufacturing the optical module.

  In an optical module in which a plurality of laser diodes including a laser diode having an oscillation wavelength of 550 nm or less are hermetically sealed in a package, it is known that a dust collection effect as described in Patent Document 1 occurs. . The dust collection effect is that contaminants remaining in the package adhere to the emission end face of the laser diode. In a laser diode having an oscillation wavelength of 550 nm or less, since the energy of the emitted laser diode is high, the dust collection effect is significant, and when the dust collection effect occurs, output degradation of the laser diode occurs. As a result, the reliability of the optical module decreases. As a contamination source causing the dust collection effect, a resin curable adhesive (for example, an ultraviolet curable resin) for bonding an optical component to another component is used. In the technique described in Patent Document 1, in order to suppress the dust collection effect, in order to bond the optical component to other components, flux-free solder that does not become a contamination source or an adhesive that does not contain Si-based organic substances is used. Yes.

JP 2004233388 A

  If a flux-free solder or an adhesive containing no Si-based organic substance is used instead of the resin curable adhesive as in Patent Document 1, the dust collection effect can be suppressed. However, when flux-free solder or an adhesive that does not contain Si-based organic substances is used, the productivity of the optical module is reduced and the manufacturing cost is increased as compared with the case where a resin-curing adhesive is used.

  It is an object of the present invention to provide an optical module and an optical module manufacturing method capable of improving productivity and reducing manufacturing cost while suppressing a decrease in reliability.

  An optical module according to an aspect of the present invention combines a plurality of laser diodes and a plurality of laser beams emitted from the plurality of laser diodes, and a multiplexing optical that emits a combined light of the plurality of laser beams. And a package for accommodating the plurality of laser diodes and the multiplexing optical system, and the package includes a support on which the plurality of laser diodes and the multiplexing optical system are mounted, and the support. A plurality of laser diodes bonded and mounted on the support, and a cap having a transmission window through which the combined light passes, and the plurality of laser diodes. The oscillation wavelength of at least one of the laser diodes is 550 nm or less, the moisture concentration inside the package is 3000 ppm or less, Multiplexing optical system is fixed to the support by a resin-curing adhesive.

  ADVANTAGE OF THE INVENTION According to this invention, while suppressing the fall of reliability, while improving productivity, the manufacturing method of the optical module which can aim at reduction of manufacturing cost can be provided.

FIG. 1 is a perspective view illustrating an example of an optical module according to the first embodiment. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. FIG. 3 is a perspective view showing the optical component mounted product in a state where the cap is removed from the optical module shown in FIG. 4 is a plan view of the optical component mounted product shown in FIG. FIG. 5 is a flowchart illustrating the method for manufacturing the optical module according to the first embodiment. FIG. 6 is a drawing for explaining a method of mounting the first to third laser diodes (LD) on the base member. FIG. 7 is a drawing for explaining a method of mounting a TEC (temperature control element) on the base member. FIG. 8 is a view showing a state in which a base member is mounted in a TEC shape. FIG. 9 is a diagram for explaining a post-process of FIG. FIG. 10 is a view showing a state in which the first to third collimating lenses are mounted on the base member. FIG. 11 is a diagram for explaining a method of adjusting the optical axis of the first collimating lens. FIG. 12 is a diagram for explaining a method of adjusting the optical axis of the second collimating lens. FIG. 13 is a diagram for explaining a method of adjusting the optical axis of the third collimating lens. FIG. 14 is a view showing a state where the first and second wavelength selective filters are mounted on the base member. FIG. 15 is a diagram for explaining a method of adjusting the optical axis of the first wavelength selective filter. FIG. 16 is a diagram for explaining a method of adjusting the optical axis of the second wavelength selective filter. FIG. 17 is a perspective view of an example of an optical module according to the second embodiment. FIG. 18 is a perspective view showing the optical component mounted product in a state where the cap is removed from the optical module shown in FIG. FIG. 19 is a perspective view of the optical module used in the experimental example. FIG. 20 is a graph plotting experimental results. FIG. 21 is a table summarizing the experimental results.

[Description of Embodiment of the Present Invention]
First, the contents of the embodiment of the present invention will be listed and described.

  An optical module according to an aspect of the present invention combines a plurality of laser diodes and a plurality of laser beams emitted from the plurality of laser diodes, and a multiplexing optical that emits a combined light of the plurality of laser beams. And a package for accommodating the plurality of laser diodes and the multiplexing optical system, and the package includes a support on which the plurality of laser diodes and the multiplexing optical system are mounted, and the support. A plurality of laser diodes bonded and mounted on the support, and a cap having a transmission window through which the combined light passes, and the plurality of laser diodes. The oscillation wavelength of at least one of the laser diodes is 550 nm or less, the moisture concentration inside the package is 3000 ppm or less, Multiplexing optical system is fixed to the support by a resin-curing adhesive.

  In the above configuration, the moisture concentration inside the package is 3000 ppm or less. Therefore, even if the multiplexing optical system is bonded to the support by a resin curable adhesive in the package, output degradation of the LD having an oscillation wavelength of 550 nm or less can be suppressed. Therefore, it is possible to suppress a decrease in the reliability of the optical module. Furthermore, since the resin curable adhesive is used for joining the multiplexing optical system to the support, it is possible to improve the productivity of the optical module and reduce the manufacturing cost.

The volume of the internal space of the package defined by the support and the cap may be 200 mm ³ or more. When the package accommodates a plurality of laser diodes and a multiplexing optical system, the volume of the internal space of the package tends to increase to 200 mm ³ or more. For such a package with a large volume, productivity can be increased by using a resin-curing adhesive that is simple in process for joining to the support of the multiplexing optical system.

  Each of the plurality of laser diodes is mounted on the support via a submount corresponding to each of the plurality of laser diodes, and each of the submounts is fixed to the support by a conductive adhesive. May be. As described above, even when a conductive adhesive is used for fixing each submount to the support, the moisture concentration inside the package is 3000 ppm or less, so that a decrease in the reliability of the optical module can be suppressed. Further, since the conductive adhesive is used for fixing each submount to the support, it is possible to improve the productivity of the optical module and reduce the manufacturing cost. Examples of the conductive adhesive are silver (Ag) paste, carbon (C) paste, and copper (Cu) paste. From the viewpoint of volume resistivity and connection resistance, an Ag paste is desirable.

  The oscillation wavelength may be 435 nm to 465 nm. Alternatively, the oscillation wavelength may be 390 nm to 420 nm.

  You may further provide the moisture absorbent arrange | positioned in the said package. The moisture concentration inside the package can be further reduced by the moisture absorbent.

  The hygroscopic agent may be provided on the inner wall of the cap. By providing the hygroscopic agent on the inner wall of the cap, a sufficient space for arranging the plurality of LDs and the multiplexing optical system can be secured on the support.

  The support may include a stem and a base member mounted on the stem, and the plurality of laser diodes and the multiplexing optical system may be mounted on the base member.

  The multiplexing optical system is a plurality of collimating lenses for a plurality of laser beams emitted from the plurality of laser diodes, and each of the plurality of collimating lenses substantially converts each of the plurality of laser beams into a collimating beam. And a plurality of wavelength selective filters that combine the plurality of laser beams substantially converted into collimated light by the plurality of collimating lenses into one laser beam.

  The moisture concentration in the package may be 2000 ppm or less. Thereby, the reliability fall of an optical module can be suppressed more.

  The moisture concentration in the package may be 1000 ppm or less. Thereby, the reliability fall of an optical module can be suppressed further.

  An optical module manufacturing method according to another aspect of the present invention combines a plurality of laser diodes and a plurality of laser beams respectively emitted from the plurality of laser diodes in a package including a support and a cap. And a combining optical system for generating combined light, and a method of manufacturing an optical module that emits the combined light from a transmission window provided in the cap, the plurality of laser diodes, and the combining optical system. A step of preparing an optical component mounting product on which the wave optical system is mounted on the support, and the cap on the support of the optical component mounting product so that the moisture concentration inside the package is 3000 ppm or less. Sealing the plurality of laser diodes and the multiplexing optical system on the support with the cap, and bonding the plurality of laser diodes. Oscillation wavelength of at least one laser diode of the The diode is at 550nm or less, in the above optical component mounting parts, the multiplexing optical system are bonded by a resin curable adhesive to the support.

  According to the above method, an optical module having a moisture concentration inside the package of 3000 ppm or less can be manufactured. Therefore, even if the multiplexing optical system is bonded to the support by a resin curable adhesive in the package, output degradation of the LD having an oscillation wavelength of 550 nm or less can be suppressed. Therefore, an optical module in which a decrease in reliability is suppressed can be manufactured. Furthermore, since the resin curable adhesive is used for joining the multiplexing optical system to the support, it is possible to improve the productivity of the optical module and reduce the manufacturing cost.

  The sealing step includes a step of baking the optical component mounted product and a cap bonded to the support in a dry air atmosphere, and the optical component mounted product that has been baked in a dry air atmosphere. And bonding the cap to the support so that the plurality of laser diodes and the multiplexing optical system included in the device are hermetically sealed by the baked cap.

  By providing the step of baking in this way and bonding the cap to the support so as to be hermetically sealed by the cap that has been baked in a dry air atmosphere, the moisture concentration can be 3000 ppm or less.

[Details of the embodiment of the present invention]
Specific examples of embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited to these exemplifications, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims. In the description of the drawings, the same reference numerals are given to the same elements, and duplicate descriptions are omitted. In the description, words indicating directions such as “up” and “down” are convenient words based on the state shown in the drawings.

(First embodiment)
As shown in FIGS. 1 to 4, the optical module 1 according to the first embodiment includes a package 10, a first laser diode (LD) 21, a second LD 22, a third LD 23, and a multiplexing optical system. 30. The optical module 1 may further include a mirror 41. Similarly, the optical module 1 may include a PD (photodiode) 42. Similarly, the optical module 1 may include a thermistor 43 (temperature measuring resistor). Below, unless otherwise indicated, the form of the optical module 1 provided with the mirror 41, PD42, and the thermistor 43 is demonstrated.

  The optical module 1 receives the first laser light L1 emitted from the first LD 21, the second laser light L2 emitted from the second LD 22, and the third laser light L3 emitted from the third LD 23. The light is multiplexed by the multiplexing optical system 30 and the combined light is emitted from the package 10. Specifically, the first laser beam L1 and the second laser beam L2 are combined by the multiplexing optical system 30 to generate the first combined beam ML1, and the first combined beam ML1 and the third laser beam are generated. The light L3 is multiplexed by the multiplexing optical system 30 to generate the second combined light ML2, and the second combined light ML2 is emitted from the package 10.

  The first to third LDs 21 to 23 emit laser light having a wavelength in the visible range. At least one of the first to third LDs 21 to 23 is an LD having an oscillation wavelength of 550 nm or less. For example, at least one of the first to third LDs 21 to 23 may have any wavelength in the wavelength range of 435 nm to 465 nm. Alternatively, at least one of the first to third LDs 21 to 23 may have any wavelength in the wavelength range of 390 nm to 420 nm.

  In the following description, the oscillation wavelength of the first LD 21 is any of the wavelength range 610 nm to 670 nm, the oscillation wavelength of the second LD 22 is any of the wavelength range 500 nm to 550 nm, and the oscillation wavelength of the third LD 23 Is a wavelength range of 435 nm to 465 nm.

  As shown in FIGS. 1 and 2, the package 10 includes a support body 11 and a cap 12, and is configured by joining the cap 12 to the support body 11. The package 10 accommodates the first LD 21, the second LD 22, the third LD 23, and the multiplexing optical system 30 in an airtightly sealed state.

  First, the structure on the support body 11 and the support body 11 is demonstrated using FIGS. In FIG. 4, illustration of wiring using bonding wires or the like is omitted. The support 11 is a member for supporting the first LD 21, the second LD 22, the third LD 23, and the multiplexing optical system 30. As shown in FIG. 2, the support 11 includes a stem 111, a TEC (Thermo-Electric Cooler) 112 that is a temperature control element, and a base member 113. A component on which the first LD 21, the second LD 22, the third LD 23, and the multiplexing optical system 30 are mounted on the support 11 is also referred to as an optical component mounting product 2. The optical component mounted product 2 corresponds to the optical module 1 with the cap 12 removed.

  The stem 111 is a plate-like member having a flat main surface 111a. An example of the material of the stem 111 is an iron alloy subjected to Ni / Au plating. Hereinafter, for convenience of explanation, the normal direction of the main surface 111a is referred to as a Z direction, and two directions orthogonal to the Z direction are referred to as an X direction and a Y direction. The X direction and the Y direction are orthogonal to each other.

  The stem 111 is provided with a lead pin group 50 </ b> A including nine lead pins 50 and a lead pin group 50 </ b> B including nine lead pins 50. The nine lead pins 50 included in the lead pin group 50A are passed in a state insulated from the stem 111 in the normal direction of the main surface 111a, and are arranged in parallel to each other. Similarly, the nine lead pins 50 included in the lead pin group 50B are passed in a state insulated from the stem 111 in the normal direction of the main surface 111a, and are arranged in parallel to each other. The lead pins 50 included in each of the lead pin groups 50 </ b> A and 50 </ b> B protrude on the main surface 111 a of the stem 111.

  The lead pin group 50A and the lead pin group 50B are arranged at a predetermined distance in the Y direction. In one embodiment, the lead pin group 50A is disposed on one edge side of the stem 111 in the Y direction, and the lead pin group 50B is disposed on the other edge side.

  A total of 18 lead pins 50 included in the lead pin group 50A and the lead pin group 50B are used for signals supplied to the anode and the cathode in each of the first to third LDs 21 to 23 and the PD 42, and to the TEC 112. Two wires are assigned for current supply, and the other lead pins 50 are assigned as GND wires.

  The TEC 112 is mounted on the main surface 111 a of the stem 111. The TEC 112 can be disposed between the lead pin group 50A and the lead pin group 50B in the Y direction. As shown in FIGS. 2 and 3, the TEC 112 is fixed to the main surface 111a by bonding the surface 112a of the TEC 112 to the main surface 111a. The surface 112a and the main surface 111a of the TEC 112 are bonded with, for example, a silver (Ag) paste. The surface 112a is a flat surface and functions as a heat dissipation surface. The wiring pads of the TEC 112 are electrically connected to the lead pins 50 through the bonding wires B8. A base member 113 is mounted on the flat surface 112b opposite to the surface 112a of the TEC 112.

  As shown in FIGS. 2, 3, and 4, the base member 113 has a first surface 113a and a second surface 113b. The base member 113 is fixed to the TEC 112 by Ag paste, for example. The base member 113 may be a conductive substrate made of a conductive material or an insulating substrate made of an insulating material.

  As shown in FIG. 4, the shape of the base member 113 in a plan view (that is, when viewed from the thickness direction of the stem 111) is a rectangular shape such as a rectangle or a square. When the planar view shape of the base member 113 is rectangular, the length of the short side of the base member 113 is about 7 mm, for example, and the length of the long side is 12 mm, for example. When the planar view shape of the base member 113 is a square, the length of one side of the base member 113 is, for example, about 10 mm. An example of the material of the base member 113 is an iron alloy subjected to Ni / Au plating.

  As shown in FIGS. 2 and 3, the height of the second surface 113b is lower than the height of the first surface 113a. That is, the base member 113 has a first surface 113a and a second surface 113b having different heights, and a step is formed by the first and second surfaces 113a and 113b. The first and second surfaces 113a and 113b are parallel to each other.

  Therefore, the base member 113 has a notch part which forms the 2nd surface 113b in the plate-shaped member which has the 1st surface 113a. In other words, the base member 113 can be regarded as a member in which an LD mounting portion that is substantially L-shaped in plan view is integrally provided on the main surface of the plate-like main body portion. In this case, in the main surface of the plate-shaped main body, an area other than the installation area of the LD mounting portion corresponds to the second surface 113b, and the surface of the LD mounting portion corresponds to the first surface 113a.

  As shown in FIGS. 2 to 4, the first surface 113 a is an LD mounting surface (or LD mounting region) on which the first to third LD 21 to LD 23 are mounted, and the thickness direction of the stem 111 ( It is substantially L-shaped when viewed from the Z direction.

  The first LD 21 emits the first laser beam L1. The first LD 21 is an LD whose oscillation wavelength is any one of the wavelength range of 610 nm to 670 nm, and the first LD 21 is, for example, a red LD. An example of the oscillation wavelength of the first LD 21 is 640 nm. The first LD 21 can be an LD chip. The first LD 21 is made of, for example, an AlGaAs ternary material, but is not limited thereto. The first LD 21 may be a material that can realize an oscillation wavelength within the above-illustrated wavelength range, that is, a material that can output light having a wavelength in the red wavelength range of about 610 nm to 670 nm.

  The first LD 21 is arranged on the base member 113 so that the optical axis direction of the first LD 21 extends in the X direction, that is, the first laser light L1 is emitted from the first LD 21 in the X direction. Mounted on. The first LD 21 is mounted on the main surface 61 a of the first submount 61, and is mounted on the first surface 113 a of the base member 113 via the first submount 61. The first LD 21 is bonded to the main surface 61a with solder such as AuSn solder or Ag paste. The first submount 61 is bonded to the first surface 113a by, for example, Ag paste (conductive adhesive). The first LD 21 is electrically connected to the first submount 61 via the bonding wire B1, and the first submount 61 is electrically connected to the lead pin 50 via the bonding wire B2. The first LD 21 emits the first laser beam L1 along the optical axis along the first surface 113a.

  The second LD 22 emits the second laser light L2. The second LD 22 is an LD whose oscillation wavelength is in the wavelength range of 500 nm to 550 nm, and the second LD 22 is, for example, a green LD. An example of the oscillation wavelength of the second LD 22 is 535 nm. The second LD 22 can be an LD chip. The second LD 22 is made of, for example, an InGaN ternary material, but is not limited thereto. The second LD 22 may be a material that can realize an oscillation wavelength within the above-illustrated wavelength range, that is, a material that can output light having a wavelength in the green wavelength range of about 500 nm to 550 nm.

  The second LD 22 is arranged so that the optical axis direction of the second LD 22 is orthogonal to the optical axis direction of the first LD 21, that is, the first laser beam L 1 emission direction from the first LD 21 and the second LD 22. It is mounted on the first surface 113a so that the emission direction of the second laser light L2 from the second LD 22 is orthogonal. The second LD 22 is mounted on the main surface 62 a of the second submount 62, and is mounted on the first surface 113 a of the base member 113 via the second submount 62. The second LD 22 is bonded to the main surface 62a with solder such as AuSn solder or Ag paste. The second submount 62 is bonded to the first surface 113a with, for example, Ag paste (conductive adhesive). The second LD 22 is electrically connected to the second submount 62 via the bonding wire B3, and the second submount 62 is electrically connected to the lead pin 50 via the bonding wire B4.

  The third LD 23 emits the third laser light L3. The third LD 23 is an LD whose oscillation wavelength is in the wavelength range of 435 nm to 465 nm, and the third LD 3 is, for example, a blue semiconductor laser. The third LD 23 can be an LD chip. The third LD 23 is made of, for example, a GaN-based material, but is not limited thereto. The third LD 23 may be a material that can realize an oscillation wavelength within the above-illustrated wavelength range, that is, a material that can output light having a wavelength in the blue wavelength range of about 435 nm to 465 nm.

  The third LD 23 is arranged so that the optical axis direction of the third LD 23 is orthogonal to the optical axis direction of the first LD 21, that is, the emission direction of the first laser light L 1 from the first LD 21 and the first LD 21. The third laser beam L3 is mounted on the first surface 113a so as to be orthogonal to the emitting direction of the third laser beam L3 from the third LD 23. Furthermore, the third LD 23 is disposed on the same side as the second LD 22 with respect to the optical axis direction of the first LD 21, and is opposite to the first LD 21 with respect to the second LD 22 in the X direction. Is arranged.

  The third LD 23 is mounted on the main surface 63 a of the third submount 63, and is mounted on the first surface 113 a of the base member 113 via the third submount 63. The third LD 23 is bonded to the main surface 63a with solder such as AuSn solder or Ag paste. The third submount 63 is bonded to the first surface 113a with, for example, Ag paste (conductive adhesive). The third LD 23 is electrically connected to the third submount 63 via the bonding wire B5, and the third submount 63 is electrically connected to the lead pin 50 via the bonding wire B6.

  In the first embodiment, the height of the laser beam emission point of the first LD 21, the height of the laser beam emission point of the second LD 22 when the first surface 113 a of the base member 113 is used as a reference, and The heights of the first to third submounts 61 to 63 are set so that the laser light emission points of the third LD 23 are equal to each other. In other words, the optical axis of the first LD 21, the optical axis of the second LD 22, and the optical axis of the third LD 23 are at substantially the same height with respect to the first surface 113 a. In addition, each 1st-3rd LD21-23 is mounted in epiup form about the height of the light emission end surface of each 1st-3rd laser beam L1, L2, L3 in each 1st-3rd LD21-23. In this case, when the first to third LDs 21 to 23 are mounted in an epi-down configuration, the heights of the first to third LDs 21 to 23 substantially coincide with the heights of the upper ends of the first to third LDs 21 to 23, respectively. It is substantially coincident with the height of the upper end of ~ 63.

  As a material of the first to third submounts 61 to 63, a material having a thermal expansion coefficient close to that of the semiconductor material constituting the first LD21, the second LD22, and the third LD23 can be used. SiC, Si, diamond or the like can be used.

  As shown in FIGS. 2 to 4, the second surface 113b is a multiplexing optical system mounting surface (or a multiplexing optical system mounting region) on which the multiplexing optical system 30 is mounted, as viewed from the Z direction. In some cases, the second surface 113b is disposed inside the first surface 113a. A wiring pad (not shown) may be provided on the second surface 113b, and the wiring pad is electrically connected to the lead pin 50 via the bonding wire B7.

  On the second surface 113b, the first collimating lens 31, the second collimating lens 32, the third collimating lens 33, the first wavelength selective filter 34, and the second wavelength included in the multiplexing optical system 30 are provided. A first sub-base member 71, a second sub-base member 72, a third sub-base member 73, a fourth sub-base member 74, and a fifth sub-base member 75 on which the selectivity filter 35 is mounted are provided. ing.

  The material of the first to fifth sub-base members 71 to 75 is a material having a thermal expansion coefficient close to that of the first to third collimating lenses 31 to 33 and the first and second wavelength selective filters 34 and 35, for example. Can be glass. The first to fifth sub-base members 71 to 75 may be made of ceramic or metal. The first to fifth sub-base members 71 to 75 are fixed to the second surface 113b by Ag paste, for example. The material of the first to fifth sub-base members 71 to 75 may be the same as that of the base member 113 and may be integrally molded with the base member 113. The areas of the mounting surfaces (upper surfaces) of the first to fifth sub-base members 71 to 75 are the first to third collimating lenses 31 to 33 and the first and second wavelength selective filters 34, It is desirable that it is an area where an amount of adhesive necessary for fixing 35 can be applied, for example, about 0.3 to 0.5 square millimeters. The thickness of the first to fifth sub-base members 71 to 75 is, for example, about 0.1 mm.

  The multiplexing optical system 30 includes a first collimating lens 31, a second collimating lens 32, a third collimating lens 33, a first wavelength selective filter 34, and a second wavelength selective filter 35.

  The first collimating lens 31 is optically coupled to the light emitting end face of the first LD 21, and collimates (collimates) the first laser light L 1 emitted from the first LD 21. An example of the focal length of the first collimating lens 31 is less than 5 mm. The first collimating lens 31 is mounted on the first sub-base member 71, and is mounted on the second surface 113 b of the base member 113 via the first sub-base member 71. The first collimating lens 31 is bonded and fixed to the first sub-base member 71 with a resin curable adhesive. Examples of the resin curable adhesive include an ultraviolet curable resin, a thermosetting resin, and a resin using both ultraviolet curing and thermal curing.

  The second collimating lens 32 is optically coupled to the light emitting end face of the second LD 22 and collimates the second laser light L2 emitted from the second LD 22. An example of the focal length of the second collimating lens 32 is the same as that of the first collimating lens 31. The second collimating lens 32 is mounted on the second sub-base member 72, and is mounted on the second surface 113 b of the base member 113 via the second sub-base member 72. The second collimating lens 32 is bonded and fixed to the second sub-base member 72 with a resin curable adhesive. An example of the resin curable adhesive used for the second collimating lens 32 is the same as the example of the resin curable adhesive for the first collimating lens 31.

  The third collimating lens 33 is optically coupled to the light emitting end face of the third LD 23, and collimates the third laser light L3 emitted from the third LD 23. An example of the focal length of the third collimating lens 33 is the same as that of the first collimating lens 31. The third collimating lens 33 is mounted on a third sub-base member 73 arranged side by side on the second sub-base member 72 in the X direction. The third collimating lens 33 is mounted on the second surface 113 b of the base member 113 via the third sub-base member 73. The third collimating lens 33 is bonded and fixed to the third sub-base member 73 with a resin curable adhesive. An example of the resin curable adhesive used for the third collimating lens 33 is the same as the example of the resin curable adhesive for the first collimating lens 31.

  The optical axes of the first to third collimating lenses 31 to 33 and the optical axes of the first to third LDs 21 to 23 are adjusted so as to substantially coincide with each other. As an example, each of the first to third submounts 61 to 63 has a thickness of 0.15 mm, and the first to third submounts 61 to 63 have first to third main surfaces 61a to 63a. The height of each of the laser light emission points of the LDs 21 to 23 is 0.1 mm, and the height of the laser light emission point with respect to the first surface 113a is 0.25 mm.

  Here, the first to third collimating lenses 31 to 33 are, for example, lenses that are held by a side-view square lens holder having a side of 1.0 mm, and the lens is arranged from one side of the lens holder in the side view. When the distance to the center is 0.5 mm and the height of the step between the first surface 113a and the second surface 113b is about 0.25 mm, the optical axis height of the first to third LDs 21 to 23 And the optical axis heights of the first to third collimating lenses 31 to 33 substantially coincide with each other.

  The height of the step between the first surface 113a and the second surface 113b in the base member 113 is the vertical alignment margin when the first to third collimating lenses 31 to 33 are aligned, and the first Considering the application thickness of the resin-curing adhesive that fixes the lens holders of the third collimating lenses 31 to 33 on the second surface 113b, it is desirable that the thickness be higher by several hundred μm than 0.25 mm. Therefore, for example, the thickness of the base member 113 itself (the thickness of the LD mounting region of the base member 113) is 1.0 mm, and the thickness of the second surface 113b of the base member 113 (the thickness of the lens mounting region of the base member 113). The height of the step between the first surface 113a and the second surface 113b is 0.6 mm.

  The first wavelength selective filter 34 is, for example, a multilayer filter formed on a glass substrate, and is mounted on the second surface 113 b of the base member 113 via the fourth sub-base member 74. The first wavelength selective filter 34 is disposed on the second surface 113b so as to be located on the intersection of the optical axes of the first and second LDs 21 and 22. The first wavelength selective filter 34 is bonded and fixed to the fourth sub-base member 74 with a resin curable adhesive. The example of the resin curable adhesive used for the first wavelength selective filter 34 is the same as the example of the resin curable adhesive for the first collimating lens 31. One surface of the first wavelength selective filter 34 is optically coupled to the first collimating lens 31, and the other surface of the first wavelength selective filter 34 is optically coupled to the second collimating lens 32. Is bound to.

  The first wavelength-selective filter 34 transmits the first laser light L1 collimated by the first collimating lens 31, and the second laser light L2 collimated by the second collimating lens 32 is secondly transmitted. Reflected to the wavelength selective filter 35 side. The optical axis of the first laser light L1 transmitted through the first wavelength selective filter 34 and the optical axis of the second laser light L2 reflected by the first wavelength selective filter 34 are substantially coincident with each other. Adjusted to As described above, the first wavelength selective filter 34 outputs the first combined light ML1 obtained by combining the first laser light L1 and the second laser light L2.

  Similar to the first wavelength selective filter 34, the second wavelength selective filter 35 is, for example, a multilayer filter formed on a glass substrate, and a fifth sub-filter is formed on the second surface 113b of the base member 113. It is mounted via a base member 75. The second wavelength selective filter 35 is disposed on the second surface 113b so as to be located on the intersection of the optical axes of the first and third LDs 21 and 23. Therefore, the second wavelength selective filter 35 is disposed on the opposite side of the first LD 21 with respect to the first wavelength selective filter 34. The second wavelength selective filter 35 is bonded and fixed to the fifth sub-base member 75 with a resin curable adhesive. An example of the resin curable adhesive used for the second wavelength selective filter 35 is the same as the example of the resin curable adhesive for the first collimating lens 31. One surface of the second wavelength selective filter 35 is optically coupled to the other surface of the first wavelength selective filter 34, and the other surface of the second wavelength selective filter 35 is the third surface. The collimating lens 33 is optically coupled.

  The second wavelength selective filter 35 transmits the first laser light L1 and the second laser light L2 (first combined light ML1) emitted from the first wavelength selective filter 34, and the third wavelength selective filter 35 The third laser light L3 collimated by the collimating lens 33 is reflected to the side opposite to the first wavelength selective filter 34 in the X direction. The optical axes of the first laser light L1 and the second laser light L2 that have passed through the second wavelength selective filter 35, and the optical axis of the third laser light L3 reflected by the second wavelength selective filter 35 Are adjusted to substantially coincide with each other. Thus, the second wavelength selective filter 35 outputs the second combined light ML2 obtained by combining the first combined light ML1 and the third laser light L3.

  When the second surface 113b of the base member 113 is used as a reference, the height of each central position of the first wavelength selective filter 34 and the second wavelength selective filter 35 is based on the second surface 113b. In this case, it is desirable that the heights of the optical axes of the first to third laser beams L1, L2, and L3 are substantially the same.

  The mirror 41 is mounted on the second surface 113 b of the base member 113 via the sixth sub-base member 76. The mirror 41 is fixed to the sixth sub-base member 76 by, for example, a resin curable adhesive. The mirror 41 is disposed on the opposite side of the first wavelength selective filter 34 with respect to the second wavelength selective filter 35 in the X direction. The mirror 41 reflects a part of the second combined light ML2 upward (on the side opposite to the base member 113) and transmits the remaining part. The mirror 41 has a right triangle shape having a slope 41a, a bottom surface 41b, and a side surface 41c in a side view. That is, the mirror 41 has a slope 41a and a bottom surface 41b that are inclined with respect to the direction in which the optical axis of the second combined light ML2 extends. The inclined surface 41a forms an angle of substantially 45 degrees with respect to the second surface 113b. The bottom surface 41 b is fixed to the base member 113.

  The inclined surface 41a of the mirror 41 reflects the second combined light ML2 in a direction intersecting the second surface 113b. For example, a translucent film is formed on the inclined surface 41a. The light reflectance on the inclined surface 41a is 95%, and the light transmittance on the inclined surface 41a is 5%. The transmitted light passing through the inclined surface 41a is refracted in the direction approaching the second surface 113b on the inclined surface 41a.

  The PD 42 is mounted on the second surface 113 b of the base member 113. The PD 42 is used for monitoring the first to third laser beams L1, L2, and L3. The PD 42 is electrically connected to the lead pin 50 by a bonding wire B9. The PD 42 is disposed obliquely below the side surface 41 c of the mirror 41. The PD 42 can detect the intensity of the second combined light ML2 by receiving light refracted on the inclined surface 41a of the mirror 41. The PD 42 desirably has high sensitivity to each of the first laser light L1, the second laser light L2, and the third laser light L3, and is, for example, a Si PD.

  The thermistor 43 is disposed on the first surface 113 a of the base member 113 on the side of the first LD 21. The thermistor 43 is fixed to the base member 113 with Ag paste, for example. The thermistor 43 is electrically connected to the lead pin 50 by a bonding wire B10.

  The package 10 will be further described with reference to FIG. The first to third LDs 21 to 23 and the multiplexing optical system 30 provided on the support 11 are hermetically sealed by the cap 12. The cap 12 has a cylindrical portion 121 and a bottom portion 122 and has a bottomed cylindrical shape.

  The cylindrical part 121 constitutes a side peripheral wall in the cap 12. A flange portion 123 may be provided at the edge of one opening of the cylindrical portion 121. An example of the shape of the cylindrical portion 121 in a plan view, in other words, a cross-sectional shape orthogonal to the central axis of the cylindrical portion 121 is, for example, a square such as a square or a rectangle.

  The bottom portion 122 is integrally provided at one end portion of the tubular portion 121 so as to close one opening of the tubular portion 121. When the flange part 123 is provided in the cylindrical part 121, the bottom part 122 closes the opening on the opposite side to the flange part 123. The bottom portion 122 is provided with a transmission window 124 through which the second combined light ML2 passes. Specifically, an opening 122a is formed in the bottom 122, and a transmission window 124 is formed by providing a transmission window member 125 in the opening 122a. The transmissive window member 125 may be a member that can transmit the second combined light ML2, and examples thereof include a resin member or a glass member made of a resin that is transmissive to the second combined light ML2. The transmission window member 125 may be a lens. For example, the transmission window member 125 may be a lens that condenses the second combined light ML2 at a point on the optical axis of the second combined light ML2.

  The cap 12 is joined to the support 11 by welding, for example, in a state where the cap 12 is disposed so that the side opposite to the bottom 122, that is, the open side (or opening side) is the support 11 side.

An internal space S _{10 of} the package 10 having the support 11 and the cap 12, that is, a space (or an accommodation space such as an LD) defined by the main surface 111 a of the stem 111 and the cap 12 included in the support 11. The volume is 200 mm ³ or more. That is, the package 10 has an inner space _{S 10} of greater volume than the volume of the internal space of the CAN package (e.g. 20mm ³ ~50mm ^3). The volume of the internal space _{S 10} of the package 10 is typically is 1200 mm ³ or less.

  The moisture concentration inside the package 10 is 3000 ppm or less, preferably 2000 ppm or less, and more preferably 1000 ppm or less. The water concentration is determined according to the method defined in MIL standard 883, specifically, METODOD. MIL-STD-883E. NO. It is a value measured in accordance with the method specified in INTERNAL WATER-VAPOR CONTENT of 1018.2. That is, the moisture concentration is monitored by measuring the gas in the vacuum chamber with a mass spectrometer while placing the optical module 1 in the vacuum chamber adjusted to a predetermined degree of vacuum. Then, the moisture concentration obtained by breaking the package in the vacuum chamber with, for example, a punch and measuring the change in moisture concentration measured with a mass spectrometer. The lower the moisture concentration, the better, but 100 ppm is the lower limit due to detection accuracy limitations.

  The optical module 1 may have a hygroscopic agent 13 as shown in FIG. The hygroscopic agent 13 can be fixed to the inner wall of the cap 12, for example. The hygroscopic agent 13 can be disposed, for example, at a location close to the third LD 23 in the bottom 122 of the cap 12 (for example, directly above the third LD 23 in the Z direction). Examples of the hygroscopic agent 13 include zeolite and calcium oxide-based materials, and examples of the form include granular, sheet-like, and paste-like forms.

  Next, an example of a method for manufacturing the optical module 1 will be described. The manufacturing method of the optical module 1 includes a preparation step S10 and a sealing step S20 as shown in FIG. Each step will be described. In the following description, the stem 111 in which the lead pin 50 is provided in advance and the base member 113 in which the first to sixth sub-base members 71 to 76 are provided in advance at predetermined positions on the second surface 113b are used. Will be explained.

[Preparation process]
In the preparation step S10, the optical component mounting product 2 shown in FIG. 3 is prepared. When the optical component mounting product 2 is prepared, the optical components on the support 11, that is, the first to third collimating lenses 31 to 33 constituting the first to third LDs 21 to 23 and the multiplexing optical system 30, and The order of mounting the first and second wavelength selective filters 34 and 35 on the support 11 is not limited as long as the desired second combined light ML2 can be generated. An example of the preparation step S10 will be described in detail.

  In the preparation step S10, as shown in FIG. 6, the first to third LDs 21 to LD23 are mounted on the main surfaces 61a, 62a, and 63a of the first to third submounts 61 to 63, respectively. The first to third LDs 21 to 23 are bonded to corresponding main surfaces 61a, 62a, and 63a with solder such as AuSn solder, for example. Subsequently, the patterns of the first to third submounts 61 to 63 from the upper surface electrodes (electrodes opposite to the first to third submounts 61 to 63) of the first to third LD21 to LD23. Then, electrical continuity is secured by wire bonding, and intermediate assemblies C1, C2, and C3 including the first to third LD21 to LD23 and the first to third submounts 61 to 63 are manufactured.

Thereafter, the intermediate assemblies C1 to C3 are bonded and fixed on the first surface 113a of the base member 113 using, for example, Ag paste so as to satisfy the following three points.
(A) Second and third from the second and third LDs 22 and 23 with respect to the emission direction of the first laser light L1 from the first LD 21 (that is, the optical axis direction of the first LD 21). The emission directions of the laser beams L2 and L3 (that is, the optical axis directions of the second and third LDs 22 and 23) are orthogonal to each other.
(B) The second and third LDs 22 and 23 are arranged on the same side with respect to the optical axis direction of the first LD 21.
(C) The second and third LDs 22 and 23 are arranged in the order of the second LD 22 and the third LD 23 from the first LD 21 side in the optical axis direction of the first LD 21.

  In the following description, the optical axis direction of the first LD 21 is defined as the X direction, and the description may be made using the Y direction and the Z direction as in the description of the configuration of the optical module 1.

  The first to third submounts 61 to 63 are first mounted on the first surface 113a of the base member 113, and then the first main surfaces 61a to 63a of the first to third submounts 61 to 63 are mounted on the first surfaces 113a. The first to third LDs 21 to 23 may be mounted, and finally electrical connection between the first to third submounts 61 to 63 and the first to third LDs 21 to 23 may be ensured by wire bonding. In this case, the process temperature when mounting the first to third submounts 61 to 63 on the first surface 113a is the same as the process temperature when mounting the first to third LDs 21 to 23 on the main surfaces 61a to 63a. The process temperature when the first to third LDs 21 to 23 are mounted on the main surfaces 61a to 63a is equal to or higher than the process temperature in the wire bonding.

  As described above, the process temperature for mounting the first to third submounts 61 to 63 on the first surface 113a is the same as that for mounting the first to third LDs 21 to 23 on the main surfaces 61a to 63a. By setting the temperature to be equal to or higher than the process temperature, it is possible to avoid a situation where the positions of the first to third submounts 61 to 63 change when the first to third LDs 21 to 23 are mounted. Also, by setting the process temperature when mounting the first to third LDs 21 to 23 to the main surfaces 61a to 63a to be equal to or higher than the process temperature in wire bonding, the first to third LDs 21 to 21 are performed when wire bonding is performed. It becomes possible to avoid the situation where the position of 23 changes.

  In parallel with the mounting of the first to third submounts 61 to 63 and the first to third LDs 21 to 23, the TEC 112 is mounted on the main surface 111a of the stem 111 as shown in FIG. . The TEC 112 is joined to the main surface 111a by Ag paste, for example. After the TEC 112 is mounted on the main surface 111a, the base member 113 is mounted on the surface 112b of the TEC 112 as shown in FIG. The base member 113 is joined to the surface 112b by Ag paste, for example.

  After the base member 113 is mounted on the surface 112b of the TEC 112, the PD 42 is mounted on the second surface 113b of the base member 113 and the thermistor 43 is mounted on the first surface 113b of the base member 113 as shown in FIG. Mounted on the surface 113a. Then, wire bonding between each lead pin 50 and the wiring pad on the base member 113, wire bonding between each lead pin 50 and the wiring pad of the TEC 112, and each lead pin 50 and each of the first to third submounts 61 to 63 are performed. Wiring such as wire bonding is performed.

  Here, the process temperature (for example, the firing temperature of the Ag paste) in mounting the TEC 112 on the main surface 111 a of the stem 111 is equal to or higher than the process temperature in mounting the base member 113 on the surface 112 b of the TEC 112. The process temperature in mounting the base member 113 on the surface 112b is equal to or higher than the process temperature in the wire bonding.

  Thus, by setting the process temperature in mounting the TEC 112 on the main surface 111a to be equal to or higher than the process temperature in mounting the base member 113 on the surface 112b, the position of the TEC 112 changes when the base member 113 is mounted. It becomes possible to avoid the situation. Further, by setting the process temperature for mounting the base member 113 on the surface 112b to be equal to or higher than the process temperature for wire bonding, it is possible to avoid a situation in which the position of the base member 113 changes when performing wire bonding. .

  Next, as shown in FIG. 10, the first to third collimating lenses 31 to 33 are mounted on the base member 113 in a state where the optical axis is adjusted.

  When the first to third collimating lenses 31 to 33 are mounted on the base member 113, the first to third collimating lenses 31 to 33 are observed while monitoring the projection patterns of the emitted light from the first to third collimating lenses 31 to 33. Optical alignment of the first to third collimating lenses 31 to 33 is performed by adjusting the positions of the collimating lenses 31 to 33.

  When the positions of the first to third collimating lenses 31 to 33 are adjusted, it is confirmed whether or not the emitted light from the first to third collimating lenses 31 to 33 is collimated. Here, if the quality of the collimator is low (the collimation property is not good), in the second combined light ML2 of the first laser light L1, the second laser light L2, and the third laser light L3. Aberrations (astigmatism and spherical aberration) become large, which may cause a problem that image quality deteriorates, for example. Therefore, in the first embodiment, the optical alignment (optical axis adjustment) of the three first to third collimating lenses 31 to 33 is performed according to the following procedure in order to maintain high collimating properties. A method for adjusting the optical axis will be described with reference to FIGS. 11 to 13 schematically show the configuration on the base member 113.

  As shown in FIG. 11, first, the relative position between the first LD 21 and the first collimating lens 31 is determined. At this time, the first collimating lens 31 is mounted on the second surface 113 b of the base member 113 via the first sub-base member 71. Then, the first collimating lens 31 is disposed on the first sub-base member 71 while causing the first LD 21 to emit light. Here, the first laser light L1 from the first LD 21 goes straight in the emission direction from the first LD 21 without being reflected. At this time, the first collimating lens 31 is disposed so that the first laser light L1 is projected onto the first projection point P1 located on the virtual plane H perpendicular to the first surface 113a. The virtual plane H can be disposed, for example, at a position away from the light emitting end face of the first LD 21 by a predetermined distance (for example, 1 m to 2 m).

  Further, the vertical position of the first collimating lens 31 is adjusted so that the optical axis of the first laser beam L1 is substantially parallel to the first surface 113a (or the second surface 113b) of the base member 113. . At this time, for example, while applying the UV curable resin to the first sub-base member 71 and securing the thickness thereof, the first collimator lens 31 is adsorbed by the collet or the like, while the collet is vertically moved (Z direction or stem 111). Adjust the position in the thickness direction). Thereby, the tilt angle of the first laser beam L1 with respect to the first surface 113a (or the second surface 113b) is adjusted.

  For example, a CCD that is a two-dimensional sensor at a position away from the light emitting end face of the first LD 21 by a predetermined distance (for example, 1 m to 2 m) in the optical axis direction of the first LD 21, that is, a position of the virtual plane H One focus of the first collimating lens 31 is arranged by aligning the first collimating lens 31 while observing the beam diameter of the first laser light L1 projected on the imaging device. And the light emitting end face of the first LD 21 are matched. Thus, by making one focal point of the first collimating lens 31 coincide with the light emitting end face of the first LD 21, the first laser light L1 output from the first collimating lens 31 becomes substantially collimated light. .

  When the distance between the first collimating lens 31 and the light emitting end face of the first LD 21 is shorter than the focal length of the first collimating lens 31, the first laser light L1 emitted from the first collimating lens 31 Becomes divergent light. On the other hand, when the distance between the first collimating lens 31 and the light emitting end face is longer than the focal length, the first laser light L1 emitted from the first collimating lens 31 becomes convergent light.

  However, in the first embodiment, as described above, since one focal point of the first collimating lens 31 and the light emitting end surface of the first LD 21 are matched, the first collimating lens 31 that emits light from the first collimating lens 31 is used. The luminous flux of one laser beam L1 is substantially parallel, and the projection pattern can be observed even at a position several m away. As described above, after making one focal point of the first collimating lens 31 coincide with the light emitting end face of the first LD 21, the ultraviolet curable resin on the first sub-base member 71 is cured to form the first collimator. The lens 31 is fixed on the first sub-base member 71.

  Next, as shown in FIG. 12, the relative position between the second LD 22 and the second collimating lens 32 is determined. At this time, the second collimating lens 32 is mounted on the second surface 113 b of the base member 113 via the second sub-base member 72. At this time, the second collimating lens 32 is arranged so that the second laser light L2 is projected onto the second projection point P2 located on the virtual plane H. The height of the second projection point P2 with respect to the first surface 113a of the base member 113 is the same as the height of the first projection point P1 with respect to the first surface 113a.

  Specifically, the alignment mirror 80 having a reflecting surface perpendicular to the first surface 113a is arranged such that the reflecting surface forms an angle of 45 ° with the optical axis of the first LD 21. It arrange | positions on the optical axis of LD22. Then, the second LD 22 is caused to emit light. At this time, the second laser light L2 is projected onto the virtual plane H. Subsequently, the vertical position of the second collimating lens 32 is adjusted so that the optical axis of the second LD 22 is substantially parallel to the first surface 113a (or the second surface 113b) of the base member 113. At this time, for example, the upper and lower positions of the collet are adjusted while adsorbing the second collimating lens 32 with a collet or the like while applying the ultraviolet curable resin to the second sub-base member 72 and securing the thickness thereof. Thereby, the tilt angle of the second laser beam L2 with respect to the first surface 113a (or the second surface 113b) is adjusted. When the vertical position of the second collimating lens 32 is adjusted, the height is the same as the height of the first projection point P1 of the first laser light L1 with respect to the first surface 113a.

  For example, when the first LD 21 and the first collimating lens 31 are aligned, an image sensor arranged on the virtual plane H is used, and the beam of the second laser light L2 projected on the image sensor. By aligning the second collimating lens 32 while observing the diameter, one focal point of the second collimating lens 32 and the light emitting end face of the second LD 22 are made to coincide. Thus, by making one focal point of the second collimating lens 32 coincide with the light emitting end face of the second LD 22, the second laser light L2 output from the second collimating lens 32 becomes substantially collimated light. .

  Subsequently, as shown in FIG. 13, the relative positions of the third LD 23 and the third collimating lens 33 are determined. First, the third collimating lens 33 is mounted on the second surface 113 b of the base member 113 via the third sub-base member 73. At this time, the third collimating lens 33 is arranged so that the third laser light L3 is projected onto the third projection point P3 located on the virtual plane H. The height of the third projection point P3 with respect to the first surface 113a of the base member is the same as the height of the first projection point P1 with respect to the first surface 113a. In this step, the third collimating lens 33 may be arranged so that the positions of the second projection point P2 and the third projection point P3 substantially coincide with each other.

  Specifically, the alignment mirror 80 having a reflecting surface perpendicular to the first surface 113a is arranged so that the reflecting surface forms an angle of 45 ° with the optical axis of the first LD 21. It arrange | positions on the optical axis of the laser beam L3. Then, the third LD 23 emits light. At this time, the third laser light L3 is projected onto the virtual plane H. Subsequently, the vertical position of the third collimating lens 33 is adjusted so that the optical axis of the third laser beam L3 is substantially parallel to the first surface 113a (or the second surface 113b) of the base member 113. To do. At this time, for example, the upper and lower positions of the collet are adjusted while adsorbing the third collimating lens 33 with a collet or the like while applying the ultraviolet curable resin to the third sub-base member 73 and securing the thickness thereof. Thereby, the tilt angle of the third laser beam L3 with respect to the first surface 113a (or the second surface 113b) is adjusted. When adjusting the vertical position of the third collimating lens 33, the height of the first projection point P1 of the first laser light L1 with respect to the first surface 113a is set to be the same as the height of the third projection. The position of the point P3 is substantially matched with the position of the second projection point P2 of the second laser light L2.

  For example, when the first LD 21 and the first collimating lens 31 are aligned, an image sensor arranged on the virtual plane H is used, and the beam of the third laser light L3 projected onto the image sensor. By aligning the third collimating lens 33 while observing the diameter, one focal point of the third collimating lens 33 and the light emitting end face of the third LD 23 are made coincident with each other. Thus, by making one focal point of the third collimating lens 33 coincide with the light emitting end face of the third LD 23, the third laser light L3 output from the third collimating lens 33 becomes substantially collimated light. .

  Next, as shown in FIG. 14, the first and second wavelength selective filters 34 and 35 are mounted on the base member 113 in a state where the optical axis is adjusted. With reference to FIGS. 15 and 16, the optical axis adjustment method of the first and second wavelength selective filters 34 and 35 will be described.

  As shown in FIG. 15, the first wavelength selective filter 34 is mounted on the second surface 113 b of the base member 113. At this time, the projection pattern of the second laser beam L2 in the imaging device used for the alignment of the first to third collimating lenses 31 to 33 is substantially matched with the projection pattern of the first laser beam L1. The angle of the first wavelength selective filter 34 is adjusted.

  Specifically, the first wavelength selective filter 34 is first placed on the optical axis of the second LD 22, and the first wavelength selective filter 34 reflects the second laser light L2 so that the first to first The projection pattern is projected onto the image pickup device such as a CCD used for adjusting the optical axes of the three collimating lenses 31 to 33, that is, the image pickup device arranged at the position of the virtual plane H described above. Then, by adjusting the deflection angle and the tilt angle of the first wavelength selective filter 34, the projection pattern of the second laser beam L2 is substantially matched with the projection pattern of the first laser beam L1. After adjusting the deflection angle and the tilt angle of the first wavelength selective filter 34 in this way to substantially match the projection pattern of the second laser light L2 with the projection pattern of the first laser light L1, the fourth The ultraviolet curable resin on the sub-base member 74 is cured, and the first wavelength selective filter 34 is fixed to the fourth sub-base member 74.

  By the first wavelength selective filter 34, the projection pattern of the first laser light L 1 is slightly translated under the influence of the thickness of the first wavelength selective filter 34. However, if the projection pattern of the second laser beam L2 is substantially coincident with the projection pattern of the first laser beam L1 that has been translated, alignment can be performed without any problem.

  Subsequently, as shown in FIG. 16, the second wavelength selective filter 35 is mounted on the second surface 113 b of the base member 113. At this time, as in the case where the first wavelength selective filter 34 is mounted, the second wavelength selection is performed so that the projection pattern of the third laser beam L3 substantially matches the projection pattern of the first laser beam L1. The deflection angle and the tilt angle of the filter 35 are adjusted. In addition, the second wavelength selective filter 35 is arranged so that the light reflecting surface of the first wavelength selective filter 34 and the light reflecting surface of the second wavelength selective filter 35 are parallel to each other. A specific adjustment method is the same as the arrangement procedure of the first wavelength selective filter 34 described above.

  Next, the mirror 41 is mounted on the second surface 113 b of the base member 113. The mirror 41 is mounted on the second surface 113b with the inclined surface 41a forming an angle of 45 degrees with respect to the second surface 113b. The mirror 41 is fixed on the sixth sub-base member 76 with an ultraviolet curable resin.

  By performing the above-described steps, the first to third LDs 21 to 23, the first to third collimating lenses 31 to 33, the first, An optical component mounting product 2 (see FIG. 4) on which the first and second wavelength selective filters 34, 35 and the like are mounted is obtained. Although the ultraviolet curable resin is exemplified for fixing the first to third collimating lenses 31 to 33, etc., any resin curable adhesive may be used.

(Sealing process)
In the sealing step S20, first, the optical component mounted product 2 and the cap 12 are baked in a dry air atmosphere (baking step). The dew point of the dry air atmosphere, the baking temperature of the baking treatment, and the treatment time can be appropriately adjusted in order to achieve a desired moisture concentration. An example of the dew point is −40 ° C. or less, an example of the baking temperature is 90 ° C. or less, and an example of the processing time is 1 hour to 12 hours. By setting the baking temperature to 90 ° C. or lower, it is possible to prevent heat from adversely affecting the characteristics of the multiplexing optical system 30. In one embodiment, the optical component mounted product 2 and the cap 12 are placed in a dry air atmosphere having a dew point of −50 ° C., and a baking process is performed at a temperature of 80 ° C. for 4 hours.

  After the baking process, the main surface 111a of the stem 111 is covered with the cap 12 in a dry air atmosphere, and the transmission window 124 of the cap 12 is provided above the inclined surface 41a of the mirror 41 (on the side opposite to the base member 113). The optical module 1 is completed by joining the cap 12 to the stem 111 in a state of being positioned by welding and configuring the package 10 (joining step). An example of the dew point in the dry air atmosphere is the same as that in the baking process. The cap 12 can be welded to the stem 111 by, for example, a resistance welder. However, if the first to third LDs 21 to 23, the first to third collimating lenses 31 to 33, the first and second wavelength selective filters 34 and 35, and the like can be hermetically sealed, the stem 111 of the cap 12 can be connected. The welding method or joining method is not limited.

  In the optical module 1, the first laser beam L1, the second laser beam L2, and the third laser beam L3 are emitted from the first LD 21, the second LD 22, and the third LD 23, respectively. The first to third laser beams L1, L2, and L3 are collimated when passing through the first collimating lens 31, the second collimating lens 32, and the third collimating lens 33, respectively. The first laser beam L1 and the second laser beam L2 are combined by the first wavelength selective filter 34 and emitted as the first combined beam ML1. Thereafter, the first combined light ML1 and the third laser light L3 are combined by the second wavelength selective filter 35 and emitted as the second combined light ML2. The second combined light ML2 composed of the first laser light L1, the second laser light L2, and the third laser light L3 is moved in the normal direction of the second surface 113b of the base member 113 by the inclined surface 41a of the mirror 41. The light is reflected, passes through the transmission window 124, and is emitted to the outside of the optical module 1.

  In the optical module 1, the multiplexing optical system 30 is fixed to the support 11 using a resin curable adhesive. Specifically, the first to fifth collimating lenses 31 to 33 and the first and second wavelength selective filters 34 and 35 are included in the base member 113 which is a part of the support 11. The sub-base members 71 to 75 are fixed using a resin curable adhesive.

When fixing a plurality of optical components such as the first to third collimating lenses 31 to 33 and the first and second wavelength selective filters 34 and 35 in the package 10 in which the volume of the internal space S ₁₀ is 200 mm ³ or more. If the above resin-type adhesive is used, the productivity can be improved and the manufacturing cost can be reduced.

  However, the resin-type adhesive is a contamination source for the target LD in an optical module in which an LD having an oscillation wavelength of 550 nm or less (hereinafter referred to as “target LD” for convenience of description) is hermetically sealed in the package. It is known. In other words, since the energy of the laser beam output from the target LD, which is an LD having an oscillation wavelength of 550 nm or less, is high, the substance released from the resin-type adhesive remaining in the package is decomposed by the laser beam, and the target LD A phenomenon known as a dust collection effect adhering to the emission end face is likely to occur. When such a dust collection effect occurs, the output of the laser beam from the target LD decreases, and the reliability of the optical module decreases. In order to avoid this, use of an adhesive that does not become a contamination source (for example, a flux-free solder described in Patent Document 1 or an adhesive containing Si-based organic matter) can be considered, but the manufacturing cost of the optical module is low. To increase. Further, the above-mentioned adhesive that does not become a contamination source tends to be complicated in the bonding process as compared with the resin curable adhesive, and it takes time for bonding. As a result, the productivity of the optical module decreases. In particular, when a plurality of LDs are provided in the package and the number of lenses, wavelength selective filters, and the like are increased accordingly, the productivity of the optical module is further reduced.

  In contrast, the inventors of the present application have found that the dust collection effect can be suppressed if the moisture concentration inside the package 10 is 3000 ppm or less. In the optical module 1, since the moisture concentration inside the package 10 is 3000 ppm or less, the output degradation of the third LD 23 is unlikely to occur due to the dust collection effect even if a resin adhesive is used. The resin curable adhesive may be less expensive than an adhesive that does not become a contamination source of the dust collection effect described above. In addition, the resin curable adhesive has a simpler bonding process and shortens the bonding time than an adhesive that does not become a contamination source of the dust collection effect described above. Therefore, in the optical module 1, it is possible to reduce the manufacturing cost while improving the productivity. Furthermore, since the dust collection effect is suppressed, it is possible to suppress a decrease in the reliability of the optical module 1. Since the dust collection effect can be suppressed as the water concentration is low, if the water concentration is 2000 ppm or less, and further 1000 ppm or less, the above-described decrease in the reliability of the optical module 1 can be further suppressed, and the productivity is improved. In addition, the manufacturing cost can be further reduced.

  As described in the method for manufacturing the optical module 1, the optical module 1 that realizes the moisture concentration is manufactured by baking the optical component mounted product 2 and the cap 12 in a predetermined dry air atmosphere after manufacturing the optical component mounted product 2. This can be realized by bonding the cap 12 to the support 11 in a dry air atmosphere after the treatment. Since the combining optical system 30 is bonded to the support 11 with a resin curable adhesive, the bonding process of the combining optical system 30 to the support 11 is simple and easy. As a result, the manufacturing method of the optical module 1 can reduce the manufacturing cost while improving the productivity.

  In the optical module 1, the first to third LDs 21 to 23 are provided on a base member 113 that constitutes a part of the support 11 via first to third submounts 61 to 63. In one embodiment, the first to third submounts 61 to 63 are bonded to the base member 113 using Ag paste. Although this Ag paste can also be a source of contamination of the dust collection effect, since the moisture concentration inside the package 10 is 3000 ppm or less, the degradation of the focused LD can be suppressed. As a result, in the optical module 1, the reliability decreases. Can be suppressed. Further, if an adhesive that does not cause contamination of the dust collection effect is used instead of the Ag paste, the manufacturing cost increases. However, since the Ag paste is used, the manufacturing cost of the optical module 1 can be further reduced. ing. When using the Ag paste, after placing the first to third submounts 61 to 63 at predetermined positions, the flux is baked and the first to third submounts 61 to 63 are attached to the support 11. What is necessary is just to adhere. Therefore, when the optical module 1 includes a plurality of components such as the first to third submounts 61 to 63 corresponding to the first to third LDs 21 to 23, productivity can be improved. Although the Ag paste is exemplified as the conductive adhesive for bonding the first to third submounts 61 to 63, the same effect can be obtained with respect to the conductive adhesive other than the Ag paste. Examples of the conductive adhesive may include carbon (C) paste and copper (Cu) paste in addition to the Ag paste. However, Ag paste is desirable from the viewpoint of volume resistivity and connection resistance.

  The dust collection effect described above tends to become more prominent when the wavelength is short, that is, when the energy of the laser beam is high. Therefore, for example, the configuration of the optical module 1 includes an LD (for example, blue-violet LD) whose oscillation wavelength is in the wavelength range of 390 nm to 420 nm, or, as illustrated, the oscillation wavelength is in the wavelength range of 435 nm to 465 nm. This is a more effective configuration including an LD (for example, a blue LD), that is, the third LD 23 illustrated in FIG.

When the optical module 1 includes the hygroscopic agent 13, it is possible to further reduce the moisture concentration in the package 10. In the embodiment in which the hygroscopic agent 13 is arranged on the inner wall of the cap 12, the space on the base member 113 is not used for the arrangement of the hygroscopic agent 13, so other optical components (first to third collimators) are formed on the base member 113. For example, it can be arranged near the third LD 23 while ensuring a sufficient space for the lenses 31 to 33 and the like. If the internal space S _{10 of the} package 10 included in the optical module 1 is 200 mm ³ or more, it is easy to ensure a region where the moisture absorbent 13 can be disposed on the inner wall of the cap 12.

  Further, in the optical module 1, the first LD 21, the second LD 22, the third LD 23, the first collimating lens 31, the second collimating lens 32, the third collimating lens 33, and the first wavelength selective filter. 34 and the second wavelength selective filter 35 are mounted on the base member 113. The base member 113 is mounted on the TEC 112. Therefore, the temperature of the first LD 21, the second LD 22, and the third LD 23 is kept constant by controlling the temperature of the TEC 112 using an ATC (Automatic Temperature Controller). Therefore, since it becomes difficult to be influenced by the ambient environmental temperature, the light emission characteristics of the first LD 21, the second LD 22, and the third LD 23 can be kept constant.

  Further, by maintaining the temperature constant by the TEC 112, it is possible to suppress fluctuations in the optical coupling state between the first to third LDs 21 to 23 and the first to third collimating lenses 31 to 33. . Therefore, the collimating properties of the first to third laser beams L1, L2, and L3 emitted from the first to third collimating lenses 31 to 33 can be maintained high. Therefore, when the second combined light ML2 is collected in an optical system (for example, a scanning optical system) connected to the subsequent stage of the optical module 1 (the output side of the second combined light ML2), astigmatism and spherical aberration are collected. Can be significantly reduced, and the possibility of color blurring can be reduced.

  In the optical module 1, the first to third collimator lenses 31 to 33 are arranged corresponding to the first to third LDs 21 to 23, respectively. And these 1st-3rd collimating lenses 31-33 are mounted on the 2nd surface 113b of base member 113 via three mutually independent 1st-3rd sub base members 71-73. ing. According to such a configuration, the resin curable adhesive for fixing the first to third collimating lenses 31 to 33 flows out to the fixing positions of the other first to third collimating lenses 31 to 33. Can be prevented. Therefore, fluctuations in the optical axes of the first laser light L1, the second laser light L2, and the third laser light L3 emitted from the first to third LDs 21 to 23 are suppressed, and the optical axis adjustment is performed with high accuracy. Can be done.

  Moreover, the optical axis adjustment in the multiplexing optical system 30 in the manufacture of the optical module 1 can be performed using, for example, FIGS. 11 to 13, 15, and 16. That is, the optical axis can be adjusted by using an image sensor disposed at a predetermined distance, for example, 1 m or 2 m from the emission end face of the first LD 21 in the optical axis direction of the first LD 21. In the optical module 1 that has undergone such optical axis adjustment, the optical axes of the first to third laser beams L1 to L3 included in the second combined light ML2 coincide immediately after emission from the combining optical system 30. At the same time, the second laser light L1 is emitted from the first LD 21 in the traveling direction (or on the optical path) at the predetermined distance (for example, 1 m or 2 m) from the emission end surface of the first LD 21. The optical axes of the first to third laser beams L1 to L3 included in the combined beam ML2 substantially coincide with each other. Therefore, the optical module 1 can output the second combined light ML2 whose optical axis is adjusted with higher accuracy.

  In particular, it is known that when the focal lengths of the first to third collimating lenses 31 to 33 are less than 5 mm, the optical axis is difficult to adjust because of being easily affected by the positional deviation of the optical components. However, for example, by adjusting the optical axis by the method described with reference to FIGS. 11 to 13, 15, and 16, as described above, the second optical axis is adjusted with higher accuracy. The combined light ML2 can be output.

(Second Embodiment)
Next, an optical module 1A according to the second embodiment will be described. FIG. 17 is a perspective view showing an appearance of the optical module 1A, and FIG. 18 is a perspective view showing a state where the cap 12A is removed from the optical module 1A. As shown in FIG. 18, the optical module 1A with the cap 12A removed is referred to as an optical component mounting product 2A as in the case of the first embodiment. In FIG. 18, for convenience, some of the bonding wires B1 to B10 and the like are not shown.

  As shown in FIGS. 17 and 18, the optical module 1A is different from the first embodiment in the direction of emission of the second combined light ML2. Therefore, the optical module 1A includes a package 10A instead of the package 10, and includes a beam splitter 44 and a PD45 instead of the mirror 41 and the PD.

  The package 10A includes a support 11A and a cap 12A. The cap 12A has the same configuration as the cap 12 except that the cap 12A is different from the cap 12 in that a transmission window 124 is provided in the cylindrical portion 121.

  The support 11 </ b> A has the same configuration as that of the support 11 except that the support 11 </ b> A includes a base member 113 </ b> A instead of the base member 113. The base member 113A has a base 90 on which the beam splitter 44 is disposed, a point that does not include the sixth sub-base member 76, and a third surface 113c on which the PD 45 is disposed. Except for the point different from the member 113, it has the same configuration as the base member 113.

  The pedestal 90 is provided at the end of the base member 113A opposite to the first LD 21 in the optical axis direction (X direction in FIG. 18) of the first LD 21. The third surface 113c is formed at the corner of the base member 113A. The corner of the base member 113A on which the third surface 113c is formed is opposite to the end of the base member 113A on which the pedestal 90 is disposed and the side on which the second and third LDs 22 and 23 are disposed. It is a corner | angular part formed with the edge part. The third surface 113c is lower than the second surface 113b.

  The beam splitter 44 is held in contact with the inclined surface 90a of the pedestal 90 included in the base member 113A. The beam splitter 44 is fixed to the pedestal 90 by, for example, a resin curable adhesive. The beam splitter 44 has an inclined surface 44a, and the inclined surface 44a forms an angle of, for example, 45 degrees with respect to the second surface 113b of the base member 113A. The PD 45 is disposed on the third surface 113c below the slope 44a.

  Further, for example, a dielectric multilayer film is attached to the inclined surface 44a of the beam splitter 44, and this inclined surface 44a has a function of reflecting a part of the second combined light ML2 downward. That is, the beam splitter 44 reflects a part of the second combined light ML2 emitted from the second wavelength selective filter 35 downward (on the third surface 113c side) and transmits the remaining part. Thus, the inclined surface 44a is a reflecting surface that reflects the first to third laser beams L1, L2, and L3. The first to third laser beams L1, L2, and L3 reflected downward on the inclined surface 44a enter the PD 45. The PD 45 can detect the intensity of the second combined light ML2 by receiving the light reflected by the inclined surface 44a of the beam splitter 44.

  Also in the optical module 1A, the moisture absorbent 13 may be provided in the cap 12A. The example of the arrangement position of the hygroscopic agent 13 is the same as in the case of the first embodiment.

  The optical module 1A of the second embodiment configured as described above is an optical module, except that the emission direction of the second combined light ML2 is different from that of the first embodiment and the structural points described above are associated therewith. The configuration is the same as that of FIG. That is, also in the optical module 1A, the moisture concentration inside the package 10A is 3000 ppm or less. Therefore, at least the same effect as that of the optical module 1 of the first embodiment can be obtained in the optical module 1A. For example, in the optical module 1A, the moisture concentration inside the package 10A is 3000 ppm or less, so that a decrease in the reliability of the optical module 1A can be suppressed, productivity can be improved, and manufacturing cost can be reduced. I can plan.

(Experimental example)
Next, a description will be given with reference to an experimental example that the output degradation of an LD having an oscillation wavelength of 550 nm or less contained in the optical module is suppressed when the moisture concentration in the package of the optical module is 3000 ppm or less. . The optical modules used in the experiment are referred to as optical modules E1, E2, E3, and E4, respectively, as shown in FIG.

  As shown in FIG. 19, the optical modules E1, E2, and E4 have the same configuration as the optical module 1A shown in FIGS. 17 and 18 except that the manufacturing conditions are different. Therefore, in the description of the optical modules E1, E2, and E4, the components corresponding to the components of the optical module 1A will be described using the same reference numerals as those of the components of the optical module 1A. The optical modules E1, E2, and E4 do not include the hygroscopic agent 13. The optical module E3 is obtained by providing the moisture absorbent 13 on the inner wall of the cap 12A in the optical module E1. Therefore, in the description of the optical module E3, the same reference numerals as those of the optical module 1A are used for the components corresponding to the components of the optical module 1A.

In the optical modules E1, E2, E3, and E4, the first LD 21 was a red LD chip, and the oscillation wavelength was 640 nm. The second LD 22 was a green LD chip, and the oscillation wavelength was 525 nm. The third LD 23 was a blue LD chip, and the oscillation wavelength was 450 nm. The volume of the internal space of the package 10A of the optical modules E1 to E4 was about 400 mm ³ .

(Optical module E1)
The optical module E1 was manufactured according to the process shown in FIG. That is, first, an optical component mounted product 2A was produced. In the manufacture of the optical component mounting product 2A, the first to third LDs 21 to 23 are bonded to the first to third submounts 61 to 63 by AuSn solder. The first to third submounts 61 to 63, the TEC 112, the PD 45, and the thermistor 43 were bonded to the base member 113 with Ag paste. As the base member 113A, one in which the first to fifth sub-base members 71 to 75 are integrally formed on the second surface 113b was used.

  The multiplexing optical system 30, that is, the first to third collimating lenses 31 to 33 and the first and second wavelength selective filters 34 and 35 are ultraviolet curable resins (manufactured by Dexerials, model number: SA1801SN, resin type: epoxy). System). The beam splitter 44 was fixed to the base 90 with an ultraviolet curable resin.

  Subsequently, the optical component mounted product 2A and the cap 12A are baked at a temperature of 80 ° C. for 4 hours in a dry air atmosphere with a dew point of −50 ° C., and then the cap 12A is resisted to the support 11 in a dry air atmosphere with a dew point of −50 ° C. Welded with a welding machine.

(Optical module E2)
An optical module E2 was manufactured in the same manner as the optical module E1, except that the temperature and processing time in the baking process in the manufacture of the optical module E1 of Experimental Example 1 were changed to 80 ° C. and 2 hours.

(Optical module E3)
The optical module E3 was manufactured by the same manufacturing method as that of the optical module E1, except that a cap 12A having an inner wall provided with a hygroscopic agent was used. As the hygroscopic agent 13, a paste-like calcium-based material was used and applied to the inner wall of the cap 12A.

(Optical module E4)
In the same manner as in the case of the optical module E1, after the optical component mounting product 2A was manufactured, the cap 12A was joined to the support 11 without performing the baking process, and the optical module E4 was manufactured. The welding method for joining the cap 12A to the support 11 is the same as in the case of the optical module E1.

(Optical module current test)
An energization test was performed on the optical modules E1, E3, and E4. In the energization test, the package temperature was set to 35 ° C., the current value was constant, and the first to third LDs 21 to 23 were caused to emit light simultaneously. The initial output of the third LD 23 was adjusted to 25 mW, the output of the third LD 23 after 300 hours from the start of the test was measured, and the output deterioration rate was calculated. The output of the third LD 23 was measured with the PD while the light emission of the first and second LDs 21 and 23 was stopped when the output was measured. When the output of the third LD 23 after 300 hours from the start of the test was I [mW], the output deterioration rate was defined as (I / 25) × 100 (%). For the first and second LDs 21 and 22 included in the optical modules E1, E3, and E4, the output deterioration rate was calculated in the same manner as the third LD23.

(Moisture concentration measurement test)
In the manufactured optical modules E1, E2, E3, and E4, the moisture concentration in the package 10A is determined by the method specified in the MIL standard 883, specifically, METODOD in MIL-STD-883E. NO. It was measured according to the method prescribed in 1018.2 INTERNAL WATER-VAPOR CONTENT. In the measurement, a quadrupole mass spectrometer (manufactured by Pfeiffer Vacuum, model: QMI422 / QMA-125) was used. The optical modules E1, E2, E3, and E4 used for the moisture concentration measurement test were different samples under the same manufacturing conditions as the sample used for the optical module energization test.

(Test results)
The results of the optical module test result and the moisture concentration measurement test are as shown in FIGS. FIG. 20 is a plot of the output deterioration rate of the optical modules E1, E3, and E4 against the moisture concentration. In FIG. 20, the horizontal axis indicates the moisture concentration (ppm), and the vertical axis indicates the output deterioration rate. In FIG. 20, the broken line connecting the plot points is a fitting curve obtained by fitting the plot points. FIG. 21 is a table summarizing the test results of the optical module energization test and the moisture concentration measurement test. The output deterioration rate of the optical module E2 in FIG. 21 is an estimated value based on the fitting curve in the figure.

  20 and 21, it can be seen that the output deterioration rate of the third LD 23 in the optical modules E1 to E4, that is, the third LD 23, decreases as the water concentration decreases. Therefore, it can be seen that output degradation of the third LD 23 can be suppressed by reducing the moisture concentration even when the ultraviolet curable resin and the Ag paste are present in the package. This is probably because moisture is involved in the movement of pollutants. Although not shown in FIGS. 20 and 21, as described above, in the optical module energization test, the output deterioration rates of the first and second LDs 21 and 22 were also calculated, but the first and second LDs 21, 22, In 22, the output degradation did not occur substantially. Therefore, it can be seen that the output deterioration is dominant in the third LD 23.

  In addition, the moisture concentration can be reduced by adjusting the processing time, for example, in the baking process. Specifically, the moisture concentration is 3000 ppm or less after baking for 2 hours or more, and 2000 ppm or less after baking for 4 hours or more. Furthermore, it can be seen that by using a hygroscopic agent, the water concentration can be further reduced (for example, 1000 ppm or less) even in the same baking treatment.

  Further, for example, the moisture concentration (ppm) corresponding to an output deterioration rate of 20% considered to be acceptable as the output deterioration rate of the third LD 23 in the optical module is about 3050 ppm. Therefore, if the moisture concentration is 3000 ppm or less, the output deterioration rate of the third LD 23 can be suppressed to 20% or less which is acceptable even when an ultraviolet curable resin and an Ag paste are used in the manufacture of the optical module. As a result, in the optical module having a moisture concentration of 3000 ppm or less in the package, productivity can be improved and manufacturing cost can be reduced while suppressing a decrease in reliability of the optical module. Here, the case where the initial light output is 25 mW is shown. However, even if the light output is made lower than this, the dust collection effect is still a problem although its progress is delayed. Therefore, the present invention is effective even for an optical module with lower light output.

  As mentioned above, although embodiment of this invention was described, this invention is not restricted to the said embodiment, It deform | transforms in the range which does not change the summary described in each claim, or applied to another thing. There may be. That is, the present invention can be variously modified without changing the gist of the present invention.

  For example, the conventional optical module has been mounted with three LDs, but the optical module may include a plurality of LDs and the oscillation wavelength of at least one LD may be 550 nm or less. Accordingly, the optical module may be provided with two LDs or may be provided with four or more LDs. The oscillation wavelengths of the plurality of LDs included in the optical module may not be different for all the LDs as illustrated.

  The support constituting the package of the optical module may not include the TEC. In this case, the support has a stem and a base member, and the base member is mounted on the stem. Moreover, the structure of a support body should just be a member in which several LD and a multiplexing optical system are mounted, unless it deviates from the meaning of this invention.

  For example, in each of the above embodiments, the first laser beam L1 collimated by the first collimator lens 31 is transmitted, and the second laser beam L2 collimated by the second collimator lens 32 is reflected forward. The first wavelength selective filter 34 is used. Instead of the first wavelength selective filter 34, a wavelength selective filter that reflects the first laser light L1 and transmits the second laser light L2 is used. It is also possible. Further, instead of the second wavelength selective filter 35 that transmits the first combined light ML1 and reflects the third laser light L3, the first combined light ML1 is reflected and the third laser light L3 is transmitted. It is also possible to use a wavelength selective filter.

In the description so far, the volume of the internal space of the package accommodating the plurality of LDs and the multiplexing optical system may be less than 200 mm ³ . However, when the package accommodates a plurality of LDs (particularly, three or more LDs) and a multiplexing optical system, the volume of the internal space of the package tends to be 200 mm ³ or more. For such a package with a large volume, the productivity can be further enhanced by using a resin-curing adhesive that is simple in process for joining to the support of the multiplexing optical system.

DESCRIPTION OF SYMBOLS 1,1A ... Optical module, 2 ... Optical component mounting product 10, 10A ... Package, 11, 11A ... Support body, 12, 12A ... Cap, 13 ... Hygroscopic agent, 30 ... Multiplexing optical system, 31 ... First Collimating lens 32 ... second collimating lens 33 ... third collimating lens 34 ... first wavelength selective filter 35 ... second wavelength selective filter 61 ... first submount 62 ... first 2 submounts, 63 ... third submount, 111 ... stem, 113, 113A ... base member, 124 ... transmission window, L1 ... first laser light, L2 ... second laser light, L3 ... third Laser light, ML1... First combined light, ML2... Second combined light, S ₁₀ .

Claims (13)

A plurality of laser diodes;
Combining a plurality of laser beams emitted from the plurality of laser diodes, and combining optical systems for emitting the combined light of the plurality of laser beams;
A package containing the plurality of laser diodes and the multiplexing optical system;
With
The package is
A support on which the plurality of laser diodes and the multiplexing optical system are mounted;
A cap that is bonded to the support and hermetically seals the plurality of laser diodes and the combining optical system mounted on the support, and has a transmission window through which the combined light passes;
Have
An oscillation wavelength of at least one of the plurality of laser diodes is 550 nm or less;
The moisture concentration inside the package is 3000 ppm or less,
The multiplexing optical system is fixed to the support by a resin curable adhesive,
Optical module. The volume of the internal space of the package defined by the support and the cap is 200 mm ³ or more.
The optical module according to claim 1. Each of the plurality of laser diodes is mounted on the support via a submount corresponding to each of the plurality of laser diodes,
Each of the submounts is fixed to the support by a conductive adhesive,
The optical module according to claim 1 or 2. The oscillation wavelength is 435 nm to 465 nm.
The optical module as described in any one of Claims 1-3. The oscillation wavelength is 390 nm to 420 nm,
The optical module as described in any one of Claims 1-3. Further comprising a hygroscopic agent disposed within the package;
The optical module as described in any one of Claims 1-5. The hygroscopic agent is provided on the inner wall of the cap,
The optical module according to claim 6. The support is
Stem,
A base member mounted on the stem;
Have
The plurality of laser diodes and the multiplexing optical system are mounted on the base member,
The optical module as described in any one of Claims 1-7. The multiplexing optical system is
A plurality of collimating lenses for a plurality of laser beams emitted from the plurality of laser diodes, wherein the plurality of collimating lenses substantially convert each of the plurality of laser beams into a collimating beam;
A plurality of wavelength-selective filters that combine the plurality of laser beams substantially converted into collimated light by the plurality of collimating lenses into one laser beam;
Having
The optical module as described in any one of Claims 1-8. The moisture concentration in the package is 2000 ppm or less.
The optical module as described in any one of Claims 1-9. The moisture concentration in the package is 1000 ppm or less.
The optical module according to claim 10. A plurality of laser diodes and a combining optical system that generates a combined light by combining a plurality of laser beams respectively emitted from the plurality of laser diodes are housed in a package including a support and a cap. A method of manufacturing an optical module that emits the combined light from a transmission window provided in the cap,
Preparing an optical component mounting product in which the plurality of laser diodes and the multiplexing optical system are mounted on the support;
A plurality of laser diodes and the multiplexing optical system on the support are obtained by bonding the cap to the support included in the optical component mounted product so that the moisture concentration inside the package is 3000 ppm or less. Sealing with the cap;
With
An oscillation wavelength of at least one of the plurality of laser diodes is 550 nm or less;
In the optical component mounting product, the multiplexing optical system is bonded to the support with a resin curable adhesive,
Manufacturing method of optical module. The sealing step includes
Baking the optical component mounted product and the cap bonded to the support in a dry air atmosphere;
In the dry air atmosphere, the support is provided so that the plurality of laser diodes and the multiplexing optical system included in the baked optical component mounting product are hermetically sealed by the baked cap. Joining the body,
Having
The manufacturing method of the optical module of Claim 12.

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